The purpose of this project is to define the mechanism or regulation of the individual globin genes during erythroid differentiation. Current efforts are focused on isolating the several globin genes fron a library of sheep genomic DNA fragments which had been cloned into E. coli using the bacteriophage vector-Charon 4A. Previous studies had identified the sheep gamma and beta(A) globin genes and had shown that these genes lie within 8 kb regions of general sequence homology. An additional clone (lambdaSGbeta(C)52) has been isolated from our Charon 4A library. This clone is of particular interest because at its 5' end are DNA sequences which represent the 3' end of the beta(C) globin gene. On the other end of this cloned DNA fragment is a globin gene which has been shown previously to encode for an embryonic globin. Thus the linkage between the beta(C) glovin gene and an embryonic globin gene has been established. Both the large introns of the beta(A) and gamma globin genes have been shown to contain repetitive DNA. Complete DNA sequencing of the gamma globin gene large intron has revealed an element bounded by short tracts of both direct and inverted repeated DNA sequences. These features are characteristic of insertion-like or transposable elements.